Offset printing ink composition

ABSTRACT

An offset printing ink composition is provided which contains a vehicle resin (III) prepared by reacting 5 to 100 parts by weight of a phenolic resin (component D) with 100 parts by weight of a modified resin (II) modified with an acid, said phenolic resin (component D) being prepared by the condensation of a phenol including an alkyl substituent group having 4 to 9 carbon atoms with formalin, said modified resin (II) modified with an acid being prepared by reacting 1 to 15 parts by weight of a component C selected from the group consisting of unsaturated carboxylic acids, unsaturated carboxylic acid anhydrides and mixtures thereof with 100 parts by weight of a resin (I) obtained by copolymerizing 5 to 50 parts by weight of a component B selected from the group consisting of drying oils, fatty acids and mixtures thereof with 100 parts by weight of a five-member cyclic compound (component A) having a conjugated double bond or bonds and a Diels-Alder addition product thereof, such as cyclopentadiene or dicyclopentadiene.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an offset printing ink composition.

2. Prior Art

Relief printing processes, lithographic printing processes including anoffset printing process, and gravure printing processes have been widelyused for preparing general printing matters. In the offset printingprocess, the inked image is once transferred from a print roller to arubber blanket, and then printed on a sheet of paper. The print rollerhas a surface composed of hydrophilic portions (non-image portions)containing water and repelling oily ink and ink-holding portions (imageportions) containing oil ink and repelling water. The most widely usedoffset printing inks are resin varnishes containing resins, such asalkylphenol resins, phenolic resins modified with rosin or maleic acidresins, which are dissolved in drying oils such as linseed oil. Thephenolic resins modified with rosin are the most commonly used resins.Although a printing ink vehicle composed of a phenolic resin modifiedwith rosin, a solvent and/or a drying oil is excellent in quality, ithas disadvantages in that it is expensive and contains rosin which is amaterial of natural origin and unstable in supply. In place of thephenolic resin modified with rosin, it has been proposed to useso-called petroleum resins synthesized by polymerizing cracked oilfractions obtained as the byproducts of petroleum or petrochemicalindustries. Although these petroleum resins have advantages that thesupply and cost thereof are stable, the qualities thereof are notsatisfactory when used as the vehicle resins for the printing inks.

The principal properties, i.e. printability, required for the printingink, particularly when used for an offset printing ink, are as follows:

(1) The ink must have an appropriate fluidity represented by theviscosity and the yield value.

(2) A good balance should be retained at the interface between thehydrophilic portion and the ink-holding portion so as to form an imageon a plane over which water and an ink contact with each other.

(3) A pigment must be uniformly dispersed in the ink.

(4) The printed face has a beautiful gloss and uniform printed mattersare obtainable.

(5) The time required for setting or drying is short and the ink doesnot suffer blocking.

(6) The printed face has a resistance against friction.

In order to prepare an offset printing ink satisfying the aforementionedproperties, the resin used therein must satisfy the followingrequirements.

(1) It must have a high softening point but it should not have highmolecular weight.

(2) It must have a polar group to improve dispersibility of a pigment,namely it must have a polar group which has a good affinity with apigment.

(3) It must be easily soluble in a hydrocarbon solvent which has a highboiling point and contains only a small amount of an aromatic compound.

(4) It must have a sufficient solubility in a drying oil, such aslinseed oil.

Particularly, with the development of printing technology in recentyears, it is required to increase the printing speed. In reply to thisrequirement, the offset rotary printing process is increasingly used. Inthe offset rotary printing process wherein the ink is heated to dryness,it is eagerly desired to use a high boiling point hydrocarbon solvent,such as a paraffin solvent, which contains an aromatic compound in anamount as small as possible, preferably no aromatic compound, to improvethe environment at the working sites and to exclude the pollutionproblem caused by the exhaust gases. However, there has not yet beendeveloped an offset printing ink having a satisfactory printability, asdescribed above. Accordingly, there is an increasing demand for anoffset printing ink having a satisfactory printability.

It has been already known from U.S. Pat. No. 3,084,147 that a resinsoluble in a hydrocarbon solvent, such as benzene, toluene, xylene,cyclohexane or isooctane, can be prepared by thermally polymerizingcyclopentadiene at a high temperature of from 250° to 350° C. in thepresence of an inert hydrocarbon solvent, such as benzene, toluene,xylenene or isooctane. The dicyclopentadiene resin prepared by thisknown method is soluble in a hydrocarbon solvent including benzene,toluene, xylene, solvent naphtha and Solvent No. 5 (Trade name producedby Nippon Oil, Co., Ltd.). However, since this dicyclopentadiene resinhas no polar group, it cannot be applied for a variety of uses due toits poor miscibility and poor adhesive property to other materials. Anink prepared by adding various solvents and pigments to theaforementioned resin cannot be used as an offset printing ink, since thedispersibility of pigments in the ink is unsatisfactory, leading touneven printed face having bad gloss.

Another proposal has been made by Japanese Patent ProvisionalPublication No. 24405/1972, wherein an acrylic ester or maleic acidanhydride is added to said dicyclopentadiene resin followed byhydrolysis to prepare a carboxylic acid-containing resin, which is thenreacted with a polyhydric alcohol and a higher unsaturated carboxylicacid to produce a resin for printing inks. However, the resin preparedin accordance with this proposal and having a high softening point togive an offset printing ink to be set and dried within a timesubstantially equal to that required for setting and drying theconventional offset printing inks, is gotten poor in solubility in ahydrocarbon solvent originated from petroleum which is used as thesolvent for the offset printing ink. As the results, the fluidity of theink prepared therefrom is gotten poor and the gloss of the ink becomesextremely worse. A further disadvantage of this resin is that it formsgels in the step of the preparation of a varnish to give a cloudyvarnish having a bad hue. On the contrary, the softening point of thisresin must be lowered to improve the solubility in the solvent,resulting in prolongation of time required for setting and drying. Forthe aforementioned reasons, the resin prepared in accordance with theprior proposal cannot be used in an offset printing ink for practicaluse.

Alternatively, U.S. Pat. No. 2,608,550 discloses a resin prepared bythermally copolymerizing dicyclopentadiene and maleic acid anhydride.However, the resin taught by this prior Patent and having a relativelylow content of maleic acid has, generally, an inconveniently highsoftening point and is poor in dispersibility of pigments and also poorin miscibility with other filler materials. If the content of maleicacid anhydride is increased to overcome the aforementioneddisadvantages, there appears a tendency of coloring and gellation andthe resultant resin becomes poor in weatherproof property.

U.S. Pat. No. 2,608,550 also discloses an alkyd resin produced from aso-called alkyd composition including a polybasic acid componentconsisting of a resin prepared by thermally polymerizingdicyclopentadiene with maleic acid anhydride. However, the alkyd resinstaught by this prior patent have, in general, high molecular weights,poor solubilities in high boiling point hydrocarbon solvents for theprinting inks and in drying oils. As the results, a printing inkprepared from any of these alkyd resins is poor in fluidity, inferior ingloss of the printed matters, and tends to scatter in the form of mistsfrom the print roller to stain papers, resulting in serious mistingproblem. For these reasons, the alkyd resins taught by the prior Patentreferred to hereinabove cannot be applied for practical use.

Although a drying oil, such as linseed oil, has been used in theconventional offset printing ink varnish, the used quantity thereoftends to be decreased with the increase in printing speed to obviate theproblems of stain of the ground region caused by the use of a drying oiland to obviate occurrence of misting and retardation of setting.

The conventional offset printing ink varnish coprises a high boilingpoint hydrocarbon solvent, an oily component such as a drying oil, and abinder resin. As the binder resin for this purpose, alkylphenol resins,phenolic resins modified with rosin and maleic acid resins have beenconventionally used. However, a varnish composition containing adecreased amount of a drying oil does not give glossy and beautifulprinted matters even when any of the known binder resins is added.

In addition, any of the known resins is far from satisfactory insolubility in a paraffin solvent, so that they are almost useless as thebinder resins in offset printing inks dissolved in paraffin solvents.

OBJECTS AND SUMMARY OF THE INVENTION

An object of this invention is to provide an offset printing inkcomposition which gives uniform printed matters having printed surfacesof beautiful gloss.

Another object of this invention is to provide an offset printing inkcomposition which is set and dried for a short period of time and doesnot suffer blocking.

A further object of this invention is to provide an offset printing inkcomposition which is improved in emulsifying property thereof and doesnot cause the misting problem.

A still further object of this invention is to provide an offsetprinting ink composition having an appropriate fluidity.

Another object of this invention is to provide an offset printing inkcomposition which is excellent in interfacial balance at the interfacesbetween the hydrophilic portions and the ink-holding portions.

Another object of this invention is to provide an offset printing inkcomposition which does not form gels or become cloudy in the step of thepreparation of a varnish to give an ink varnish having a good hue.

Another object of this invention is to provide an offset printing inkcomposition containing a vehicle resin which has a good solubility in ahigh boiling point hydrocarbon solvent for the ink and in a drying oil.

Another object of this invention is to provide an offset printing inkcomposition containing a vehicle resin which is soluble in a paraffinsolvent and has an excellent printability.

Another object of this invention is to provide an offset printing inkcomposition containing a vehicle resin which achieves an excellentprintability even with the addition of relatively small amount of adrying oil.

The above and other objects of the invention and the advantageousfeatures thereof will become apparent from the following detaileddescription.

Specifically, the offset printing ink composition provided by thisinvention contains a vehicle resin (III) prepared by reacting 5 to 100parts by weight of a phenolic resin (component D) with 100 parts byweight of a modified resin (II) modified with an acid, said phenolicresin (component D) being prepared by the condensation of a phenolincluding an alkyl substituent group having 4 to 9 carbon atoms withformalin, said modified resin (II) modified with an acid being preparedby reacting 1 to 15 parts by weight of a component C selected from thegroup consisting of unsaturated carboxylic acids, unsaturated carboxylicacid anhydrides and mixtures thereof with 100 parts by weight of a resin(I) obtained by copolymerizing 5 to 50 parts by weight of a component Bselected from the group consisting of drying oils, fatty acids andmixtures thereof with 100 parts by weight of a five-member cycliccompound (component A) having a conjugated double bond or bonds andrepresented by the general formula of: ##STR1## (wherein H is hydrogen:R is an alkyl group having 1 to 3 carbon atoms; m and n are zero orintegers of not less than 1 and are in the relation of m+n=6) and/or aDiels Alder addition product thereof.

DESCRIPTION OF THE INVENTION

The present invention will now be described more specifically.

In the composition of this invention, as the component (A), used is afive-member cyclic compound having a conjugated double bond or bondsand/or a Diels-Alder addition product thereof represented by thefollowing general formula of: ##STR2## (wherein H is hydrogen;R is analkyl group having 1 to 3 carbon atoms; m and n are zero or integers ofnot less than 1 and are in the relation of m+n=6)

Specific examples of the five-member cyclic compounds which may bepreferably used on an industrial scale include cyclopentadiene andmethylcyclopentadiene, and the examples of preferable Diels-Alderaddition product include dicyclopentadiene,cyclopentadiene-methylcyclopentadiene codimer and tricyclopentadiene.Mixture of the aforementioned compounds may be also used preferably.Amongst them, cyclopentadiene, dicyclopentadiene and a mixture thereofare the most preferred.

It is not essential that the purity of the component (A) should be high.However, it is preferred that 80 wt.% or more of cyclopentadiene,dicyclopentadiene or an alkyl-substituted derivative thereof is presentin the starting material. For example, it may be possible to use aconcentrated fraction obtained by thermally dimerizing cyclopentadieneand/or methylcyclopentadiene contained in a C₅ fraction produced bycracking naphtha at a high temperature to obtain a mixture ofdicyclopentadiene, dimethylcyclopentadiene,cyclopentadiene-methylcyclopentadiene codimer, cyclopentadiene-isoprenecodimer and cyclopentadiene-piperylene codimer, followed by removing themajor part of C₅ fractions such as C₅ olefins and C₅ paraffins by meansof distillation.

Further, the component (A) may contain an additional unsaturatedcompound, particularly unsaturated aromatic compound, in an amount lessthan that of the five-member cyclic compound and or/the Diels-Alderaddition product thereof. For example, styrene, α-methylstyrene,vinyltoluene, indene, methylindene and mixtures thereof may be used asthe additional unsaturated compound, and the so-called C₉ fractionobtained as a by-product of the cracking of naphtha and the like ispreferred from the industrial point of view.

The component (B) used in this invention is selected from the groupconsisting of drying oils, fatty acids and mixtures thereof.

The drying oils which may be used as the component (B) in this inventioninclude vegetable and animal oils and fats having the iodine values ofnot less than 120, the particularly preferred being drying vegetableoils, such as linseed oil, tung oil, soy-bean oil and dehydrated castoroil. The boiled oils obtained by subjecting the aforementioned dryingoils to thermal processing may be used.

The fatty acids which may be used as the component (B) in this inventioninclude saturated or unsaturated synthetic fatty acids, such as myristicacid, palmitic acid, stearic acid, oleic acid, linoleic acid andlinolenic acid, and fatty acids of natural origins, such as fatty acidsof linseed oil and fatty acids of tall oil. Tall oil mainly composed offatty acids may also be used as the component (B) of this invention.

A mixture of two or more of the aforementioned compounds may be used asthe component (B).

In this invention, the resin (I) is prepared by reacting 100 parts byweight of the component (A) with 5 to 50 parts, preferably 10 to 40parts, by weight of the component (B) in the presence or absence of acatalyst. When the reaction is carried out in the absence of a catalyst,the mixture of said components (A) and (B) is heated at 200° to 300° C.for 30 minutes to 15 hours, preferably 1 to 7 hours, to prepare theresin (I). When a catalyst is used, a Friedel-Crafts catalyst, such asboron trifluoride, complexes thereof with phenol, ether or acetic acid,or aluminium chloride, is added to a monomer mixture in an amount of 0.1to 10 wt.%, preferably 0.3 to 2 wt.% based on the total weight of themonomers, and the mixture is reacted at a reaction temperature of from -(minus) 30° C. to 100° C., preferably 0 to 50° C., for a reaction timeof from 10 minutes to 20 hours, preferably for 1 to 15 hours.

In order to obtain a final binder or vehicle resin having a particularlyexcellent solubility in a paraffin solvent, 5 to 100 parts, preferably10 to 50 parts by weight of a straight-chain α-olefin may be included inaddition to the component (B) based on 100 parts by weight of thecomponent A. By the addition of an α-olefin, the solubility of the finalbinder or vehicle resin in a paraffin solvent is remarkably improved,whereby the printability of the printing ink containing the resin isalso improved.

The preferable straight-chain α-olefins are those having 4 to 40 carbonatoms, the most preferred being those having 6 to 20 carbon atoms.

Commercially available pure products may be, of course, used as thestraight-chain α-olefins. However, from the industrial point of view, itis recommended to use mixed α-olefins prepared by (1) theoligomerization of ethylene or (2) the thermal cracking of paraffinwaxes.

By the oligomerization of ethylene as set forth by (1) above,straight-chain α-olefins having even numbers of carbon atoms areseparated at high purity and no other isomers are contained in theseparated product. By the thermal cracking of paraffin waxes as setforth by (2) above, α-olefins are produced at a purity of about 90%, thebalance being branched chain olefins, diolefins and naphthene, and theproduct as such may be used in this invention without any inconvenience.

More specific examples of the α-olefins include 1-hexene, 1-heptene,1-octene, 1-nonene, 1-dodecene, 1-tetradecene, 1-hexadecene,1-octadecene, 1-eicosene and mixtures thereof. An olefin mixtureproduced by the process as set forth by (1) above is commerciallyavailable from Mitsubishi Kasei Co., Ltd. under the Trade Trade Name ofDialene, and a product produced by the process as set forth by (2) aboveis commercially available from Shevron Corporation under the Trade Nameof Shevron α-Olefin. A mixture of two or more of the α-olefins describedabove may be used.

If the quantity of the component (B) used in the preparation of theresin (I) in this invention is less than the range mentioned above anddefined in the claims, the advantageous effect obtained by the additionthereof does not reach the satisfactory level. On the contrary, if thequantity of the component (B) exceeds the defined range, the yield ofthe resin (I) is reduced considerably and the softening point of theresin is lowered.

According to this invention, the resin (I) prepared as aforementioned isallowed to react with the component (C) selected from the groupconsisting of unsaturated carboxylic acids, unsaturated carboxylic acidanhydrides and mixtures thereof. Preferable examples of the unsaturatedcarboxylic acids and anhydrides thereof which may be used in thisinvention include monohydric or polyhydric unsaturated carboxylic acidsand anhydrides thereof having generally 3 to 32, more preferably 3 to15, carbon atoms, the representative being acrylic acid, methacrylicacid, maleic acid, maleic acid anhydride, tetrahydrophthalic acid andanhydride thereof, fumaric acid, citraconic acid, itaconic acid andfatty acids of drying oils such as fatty acids of linseed oil andmixtures thereof. The most preferable are maleic acid and maleic acidanhydride.

The added ratio of the unsaturated carboxylic acid or anhydride thereofto the resin (I) is such that 1 to 15 parts, preferably 1 to 10 parts,by weight of the former is added to 100 parts by weight of the resin(I). If the quantity of unsaturated carboxylic acid or anhydride thereofis less than the range as mentioned above and defined in the claims, theformed resin is poorly improved as a resin having polar groups due tothe lack of polar groups. When such a resin is used as the vehicle resinfor printing ink, the dispersibility of pigments, the fluidity of theink and the printability are unsatisfactory.

On the contrary, if the quantity of the unsaturated carboxylic acid oranhydride thereof is more than the defined range, the content of polargroups contained in the resultant resin becomes too high, leading topoor solubility in a solvent and disadvantageous tendency of colorchange or gellation of the resin. When such a resin is used in aprinting ink, the solubility of the resin in a hydrocarbon solvent atthe step of preparing an ink varnish is gotten poor to deteriorate thefluidity of the ink and the gloss of the printed mattersdisadvantageously. The aforementioned reaction for modifying the resinwith an acid may be effected at a temperature of from 100° to 300° C.,preferably 150° to 250° C., in the presence of a known radical reactioninitiator, such as an organic peroxide, for 30 minutes to 15 hours,preferably 1 to 8 hours. If an unsaturated polycarboxylic acid or ananhydride thereof is used, it is preferred that the reaction be carriedout without using a catalyst. If an unsaturated monocarboxylic acid oran anhydride thereof is used, it is preferred that the reaction becarried out in the presence of a catalyst.

The modified resin according to this invention and modified with an acidmay be produced by the following one-step process.

An unsaturated carboxylic acid or an anhydride thereof may be added atthe initial or intermediate stage of the step for thermally polymerizingthe mixture of the components (A) and (B), and the admixture isthermally polymerized at a temperature of from 200° to 300° C. in thepresence or absence of a solvent.

In this invention, the modified resin (II) modified with an acid may beesterified by the use of an alcohol to control the solubility andsoftening point of the resultant resin (II) or to control the molecularweight of the vehicle resin (III). The alcohols used for this purposeinclude monohydric or polyhydric alcohols. Monohydric alcohols havingnot less than 6 carbon atoms, preferably 8 to 18 carbon atoms, areparticularly preferred to improve the solubility of the final binder orvehicle resin (III). The quantity of the alcohol should be such that themolar ratio of the carboxylic group to the alcohol group contained inthe modified resin (II) is in the range of 1:0˜1.0 and the molar ratioof the carboxylic acid anhydride group to the alcohol group contained inthe modified resin (II) is in the range of 1:0˜2.0. The esterificationmay be effected firstly by heating to melt the modified resin (II)modified with an acid or dissolving the same in a hydrocarbon solvent,such as benzene, toluene or xylene, followed by the addition of analcohol, and reacting at 150° to 250° C. for 30 minutes to 10 hours,preferably 1 to 15 hours.

According to this invention, the modified resin (II) modified with anacid is further reacted with an alkyl substituted phenolic resin(component D) to obtain the intended binder or vehicle resin (III). Thephenolic resins used in this invention include the condensation productsof phenols including alkyl substituent groups having 4 to 9 carbon atomswith formalin. Specific examples of phenols which are preferred from theindustrial point of view include p-tert-butylphenol, sec-butylphenol,p-tert-octylphenol and nonylphenol. Phenol resins prepared from phenolshaving no substituent group or cresols are not preferred, since thesolubilities of the resultant binder or vehicle resins in high boilingpoint hydrocarbon solvents are poor. If a phenolic resin prepared fromformalin and a phenol including a substitutent group having not lessthan 10 carbon atoms is used, the softening point of the resultantbinder or vehicle resin is extremely lowered to a level unsuited for theprinting ink.

Instead of reacting the modified resin (II) with a phenolic resin,formaldehyde and a phenol may be reacted in the presence of the modifiedresin (II) using an acid or alkali catalyst or without using a catalystto obtain the intended binder or vehicle resin modified with a phenolicresin.

5 to 100 parts, preferably 10 to 50 parts, by weight of the modifierphenolic resin may be added to 100 parts by weight of the modified resin(II) modified with an acid. If the qauntity of the phenolic resin isless than the aforementioned range, the printing ink produced by usingthe resultant vehicle resin is unsatisfactory in fluidity and cannotgive printed matters of satisfactory gloss. On the contrary, if thequantity of the phenolic resin exceeds the aforementioned range, thesolubility of the resultant vehicle resin in a solvent for the printingink is gotten poor and the cost is disadvantageously increased.

The resin (II) may be modified with a phenolic resin simply by mixingthe resin (II) with the phenolic resin to obtain a mixture which ismelted and heated at 150° to 250° C. for 30 minutes to 10 hours,preferably 1 to 5 hours. If necessary, an acid catalyst, such as oxalicacid, toluenesulfonic acid or a Friedel-Crafts catalyst, or an alkalicatalyst, such as a metal oxide or metal hydroxide or ammonia, may beused.

It is desirous that the binder or vehicle resin (III) have a softeningpoint of not lower than 100° C., preferably higher than 130° C. If thesoftening point of the vehicle resin (III) is lower than 100° C., theprinting ink prepared therefrom is apt to suffer misting and blockingand the drying speed of the printing ink is extremely lowered.

It is desirous that the acid value of the vehicle resin (III) be 5 to50, preferably 5 to 20. If the acid value of the resin (III) is lowerthan the aforementioned range, the printing ink prepared therefrom has apoor solubility. On the contrary, if the acid value of the resin (III)exceeds the aforementioned range, the solubility thereof in a paraffinsolvent becomes poor and the offset printing ink prepared therefrom hasa poor resistance to emulsification.

The offset printing ink of this invention may be prepared using thevehicle resin (III) modified with an acid and a phenolic resin, asdescribed above, in accordance with a known method. For instance, 100parts by weight of the vehicle resin (III) is dissolved at roomtemperature or under heating in a mixture composed of 50 to 200 parts byweight of a high boiling point hydrocarbon solvent and 10 to 100 parts,preferably 10 to 50 parts, by weight of a drying oil to prepare avarnish having a viscosity of 200 to 600 poises at room temperature. Anink composition according to this invention may be obtained by addingone or more pigments to the varnish and kneading by means of rollers orother kneaders.

The high boiling point hydrocarbon solvents which may be used in thisinvention should have the boiling points ranging from 200° to 350° C.,preferably 250° to 330° C., and aromatic compound contents thereofshould be not higher than 50 wt.%, preferably less than 30 wt.%.

According to this invention, high boiling point paraffin solvents havingboiling points ranging within 200° to 350° C. and containingsubstantially no aromatic compound may be used. As the oily componentfor the drying oil and the like, long oil alkyd resins may also be usedother than drying oils including linseed oil and tung oil.

EXAMPLES OF THE INVENTION

The present invention will be described more specifically with referenceto some examples thereof. However, it should be appreciated here thatthe following examples are to be construed as illustrative only and thepresent invention is not limited only to the examples given below.

SYNTHESIS EXAMPLE 1

850 g of 97% dicyclopentadiene and 250 g of linseed oil were chargedinto an autoclave having a capacity of 2 liters, and heated at 260° C.for 3.5 hours in the nitrogen atmosphere under agitation. The autoclavewas cooled after the completion of heating, and the content in theautoclave was distilled at 210° C./2 mmHg to remove the unreactedmaterials and oligomers. 920 g of a Resin (I-1) was left in theautoclave. The softening point of the Resin (I-1) was 136.5° C.

150 g of the Resin (I-1) was heated to 200° C. to melt the same, addedwith 4.5 g of maleic acid anhydride, and reacted for 4 hours underagitation to obtain a Modified Resin (II-1) modified with maleic acidanhydride. The softening point of the Modified Resin (II-1) was 147.0°C. and the acid value thereof was 13.5. Subsequently, 100 g of theModified Resin (II-1) was added with 17.6g of a resol-type phenolicresin which had been prepared by the condensation reaction betweenp-tert-octylphenol and formalin, and reacted at 200° C. for 2 hours toobtain a Vehicle Resin (III-1) having a softening point of 169.5° C. andan acid value of 12.7.

SYNTHESIS EXAMPLE 2

800 g of 97% dicyclopentadiene and 200 g of tall oil were charged intoan autoclave having a capacity of 2 liters, and reacted at 260° C. for 6hours. The following procedures were similar to Synthetic Example 1 toobtain 925 g of a Resin (I-2). The softening point of the Resin (I-2)was 138.5° C.

150 g of the Resin (I-2) was heated to 200° C. to melt the same, addedwith 7.5 g of maleic acid anhydride, and reacted for 3 hours underagitation to obtain a Modified Resin (II-2) modified with maleic acidanhydride. The softening point of the Modified Resin (II-2) was 158.0°C. and the acid value thereof was 24.2. Subsequently, 100 g of theModified Resin (II-2) was added with 4.2 g of decanol, and heated andagitated at 200° C. for one hour. Then, 20.2 g of a resol-type phenolicresin which had been prepared by the condensation reaction betweenp-nonylphenol and formalin was added, and reacted at 200° C. for 3 hoursto obtain a Vehicle Resin (III-2) having a softening point of 160.5° C.and an acid value of 19.4.

SYNTHESIS EXAMPLE 3

800 g of 97% dicyclopentadien, 100 g of linseed oil and 100 g of1-hexene were charged into an autoclave having a capacity of 2 liters,and reacted at 280° C. for 2 hours. The following procedures weresimilar to Synthesis Example 1 to obtain 932 g of a Resin (I-3) having asoftening point of 146.0° C.

150 g of the Resin (I-3) was heated to 200° C. to melt the same, addedwith 4.5 g of maleic acid anhydride, and reacted for 3 hours underagitation to obtain a Modified Resin (II-3) modified with maleic acidanhydride. The softening point of the Modified Resin (II-3) was 155.0°C. and the acid value thereof was 13.7. Subsequently, 100 g of theModified Resin (II-3) was added with 17.6 g of a resol-type phenolicresin which had been prepared by the condensation reaction betweenp-tert-octylphenol and formalin, and reacted at 200° C. for 2 hours toobtain a Vehicle Resin (III-3) having a softening point of 175.0° C. andan acid value of 12.2.

SYNTHESIS EXAMPLE 4

The by-product C₅ fraction (Boiling Point: 28°˜60° C.) obtained at thestep of producing ethylene and propylene through steam cracking ofnaphtha was heated at 120° C. for 4 hours and distilled to remove theunreacted C₅ fraction to obtain a mixture containing 85% ofdicyclopentadiene and the reminder of codimers of cyclopentadiene withisoprene or piperylene. 850 g of this mixture containing 85% ofdicyclopentadiene and 250 g of linseed oil were charged in an autoclavehaving a capacity of 2 liters, and reacted at 260° C. for 4 hours. Thefollowing procedures were similar to Synthesis Example 1 to obtain 872 gof a Resin (I-4) having a softening point of 137.0° C.

150 g of the Resin (I-4) was heated at 200° C. to melt the same, addedwith 5.3 g of maleic acid anhydride, and reacted for 4 hours underagitation to obtain a Modified Resin (II-4). The softening point of theModified Resin (II-4) was 148.5° C. and the acid value thereof was 16.9.Subsequently, 100 g of the Modified Resin (II-4) was added with 3.0 g of2-ethylhexanol, and heated and agitated at 200° C. for 2 hours. Then,18.2 g of a resol-type phenolic resin which had been prepared by thecondensation reaction between p-tert-octylphenol and formalin was added,and reacted at 200° C. for 2 hours to obtain a Vehicle Resin (III-4)having a softening point of 157.5° C. and an acid value of 14.1.

COMPARATIVE SYNTHESIS EXAMPLE 1

1000 g of 95% dicyclopentadiene and 400 g of xylene which acted as asolvent were charged into an autoclave having a capacity of 2 liters,and reacted at 260° C. for 3 hours. The following procedures weresimilar to Synthesis Example 1 to obtain 800 g of a Resin (I-a) having asoftening point of 152.0° C.

150 g of the Resin (I-a) was heated at 200° C. to melt the same, addedwith 5.3 g of maleic acid anhydride, and reacted for 3 hours underagitation to obtain a Modified Resin (II-a). The softening point of theModified Resin (II-a) was 165.0° C. and the acid value thereof was 16.5.Subsequently, 100 g of the Modified Resin (II-a) was added with 3.0 g ofdecanol, and heated and agitated at 200° C. Then, 18.2 g of a resol-typephenolic resin which had been prepared by the condensation reactionbetween p-tert-octylphenol and formalin was added, and reacted at 200°C. for 2 hours to obtain a Vehicle Resin (III-a) having a softeningpoint of 170.5° C. and an acid value of 13.9.

COMPARATIVE SYNTHESIS EXAMPLE 2

100 g of the Resin (I-1) obtained in Synthesis Example 1 was heated to200° C. to melt the same, and added with 17.6 g of a resol-type phenolicresin which had been prepared by the condensation reaction betweenp-tert-octylphenol and formalin. The mixture was heated and agitated at200° C. for 2 hours to obtain a Vehicle Resin (III-b) having a softeningpoint of 155.0° C.

Varnishes were prepared by using Vehicle Resin (III-1)˜(III-4) and(III-a)˜(III-b) obtained in Synthesis Examples 1˜4 and ComparativeSynthesis Examples 1 and 2 and also using the Modified Resin (II-1) anda control resin. Inks were prepared by using these varnishes, and theproperties of the inks were tested. The test results are shown in thefollowing Table under the captions of Examples 1˜4 and ComparativeExamples 1˜4.

PREPARATION OF VARNISH

50 g of each of the vehicle resins was added with 20 g of linseed oil,and heated at 240° C. for 90 minutes. Then, an appropriate amountranging within 20 to 40 g of a petroleum hydrocarbon solvent (NISSEKISolvent No. 5; see Remark 1 given below) to control the viscosity of theresultant varnishes within the range of 500˜600 poises.

Preparation of Ink:

Using each of the varnishes, an ink was prepared in accordance with thefollowing prescription using a mixing roller assembly composed of threerollers.

Prescription of Ink:

    ______________________________________                                        Pigment (Carmine 6B; see Remark 2                                             given below)           14 grams                                               Varnish                50 grams                                               Solvent (NISSEKI Solvent No. 5)                                                                       5 grams                                               Wax Compound            2 grams                                               Drier (Cobalt Naphthenate)                                                                           0.3 grams                                              ______________________________________                                    

Test Method and Test Result on the Properties of Ink:

Gloss:

0.4 cc of each ink was applied on art paper, using a RI Tester (seeRemark 3 given below), and allowed to stand for 24 hours. The gloss ofthe dried ink was determined, using a 60 degrees-60 degrees glossmeter.

Setting Time:

0.4 cc of each ink was applied on a sheet of art paper, using theaforementioned RI Tester, and another blank sheet of art paper wasoverlaid on the inked face and pressed using the roller of the RITester. The interval of time from the time at which the ink was appliedto the time at which the blank sheet of art paper was overlaid on theinked face was varied to find the interval of time required for the inknot to stick to the blank sheet of art paper.

Misting:

2.4 cc of each ink was put on the Inkometer (see Remark 4 given below)rotating at 1200 rpm. Scattering of ink on the art paper spread beneaththe roller after the lapse of 3 minutes was observed.

Drying Time:

0.4 cc of each ink was applied on a sheet of art paper using theaforementioned RI Tester, and the time required for the ink to be driedwas determined, using a tester for detecting the dryness of ink (seeRemark 5 given below).

Emulsification Property of Ink:

Water was added to each of the prepared inks to emulsify the ink, andthe fluidity of emulsified ink was determined. Offset printing inks are,in general, partially emulsified when they contact with water at theprinting step. Only the inks which give emulsions having good fluiditycan be applied for practical uses.

Control Resin:

A phenolic resin modified with rosin produced by Dainippon Ink &Chemical Co., Ltd. and commercially available under the Trade Name ofBeckacite 1126HV.

Remark 1:

A solvent for ink having boiling points of 276°˜311° C. and containing23 wt.% of aromatic compounds, and produced by Nippon Oil CompanyLimited.

Remark 2:

Produced by Toyo Ink Mfg. Co., Ltd.

Remark 3:

A tester for testing printability and produced by Akira Seisakusho Co.,Ltd.

Remark 4:

Produced by Toyo Seiki Co., Ltd.

Remark 5:

A tester produced by Toyo Seiki Co., Ltd.

                                      TABLE                                       __________________________________________________________________________                  Viscosity                                                                           Gloss                                                                   of Varnish                                                                          of the                                                                            Setting                                                                           Drying     Emulsification                                       (poise,                                                                             Printed                                                                           Time                                                                              Time       Property of                                   Used Resin                                                                           at 25° C.)                                                                   Face                                                                              (min.)                                                                            (hr.)                                                                             Misting                                                                              Ink                                    __________________________________________________________________________    Example 1                                                                            III-1  570   61  6   3.0 Not-observed                                                                         Good                                   Example 2                                                                            III-2  550   62  6   3.0 Not-observed                                                                         Good                                   Example 3                                                                            III-3  560   66  8   3.0 Not-observed                                                                         Good                                   Example 4                                                                            III-4  520   62  6   3.0 Not-observed                                                                         Good                                   Comp. Ex. 1                                                                          III-a  510   46  7   3.0 Observed                                                                             Little Poor                            Comp. Ex. 2                                                                          III-b  570   46  6   3.0 Observed                                                                             Little Poor                            Comp. Ex. 3                                                                          II-1   590   44  10  4.5 Observed                                                                             Poor                                   Comp. Ex. 4                                                                          Control Resin                                                                        550   57  6   3.0 Not-observed                                                                         Little Poor                            __________________________________________________________________________

Referring to Examples 1 to 4 shown in the Table, it should be clear thatthe offset printing ink compositions according to this invention areexcellent in gloss and good in emulsification, misting, setting anddrying properties.

In contrast thereto, an ink using a vehicle resin which contains neithera drying oil nor a fatty acid component is unsatisfactory in that thegloss of the printed face is poor with attendant misting and in that theemulsification property thereof is unsatisfactory, as will be clear fromCompative Example 1 shown in the Table.

Comparative Example 2 is an exemplified ink composition prepared byusing a resin which has not been modified with an acid, and shows thatthe gloss and emulsification property of such an ink are unsatisfactoryand that the resin suffers misting.

In Comparative Example 3, a resin which has not been modified with aphenolic resin is used. This Comparative Example shows that an inkprepared by using such a resin is unsatisfactory in gloss, setting,drying and emulsification properties and suffers misting.

In comparative Example 4, an ink is prepared by using a known controlresin commonly used in the art. This known resin is a phenolic resinmodified with rosin. It will be understood by comparing the examples ofthis invention with this Comparative Example that the gloss andemulsification property the offset printing ink compositions accordingto this invention are improved over these of the conventional inkcomposition prepared by using the known phenolic resin modified withrosin.

Although the present invention has been described with particularreference to preferred embodiments, it will be apparent to those skilledin the art that variations and modifications may be made withoutdeparting from the essential spirit and scope of the invention. It isintended to include all such variations and modifications.

What is claimed is:
 1. An offset printing ink composition containing avehicle resin (III) prepared by reacting 5 to 100 parts by weight of aphenolic resin (component D) with 100 parts by weight of a modifiedresin (II) modified with an acid, said phenolic resin (component D)being prepared by the condensation of a phenol including an alkylsubstituent group having 4 to 9 carbon atoms with formalin, saidmodified resin (II) modified with an acid being prepared by reacting 1to 15 parts by weight of a component C selected from the groupconsisting of unsaturated carboxylic acids, unsaturated carboxylic acidanhydrides and mixtures thereof with 100 parts by weight of a resin (I)obtained by thermally copolymerizing at a temperature of from 200° C. to300° C. 5 to 50 parts by weight of a component B selected from the groupconsisting of drying oils, fatty acids and mixtures thereof with 100parts by weight of a five-member cyclic compound (component A) having aconjugated double bond or bonds and represented by the general formulaof: ##STR3## (wherein H is hydrogen; R is an alkyl group having 1 to 3carbon atoms; m and n are zero or integers of not less than 1 and are inthe relation of m+n=6) and a Diels-Alder addition product thereof.
 2. Anoffset printing ink composition according to claim 1, wherein saidfive-member cyclic compound and said Diels-Alder addition productthereof (component A) is selected from the group consisting ofcyclopentadiene, methylcyclopentadiene, dicyclopentadiene,cyclopentadienemethylcyclopentadiene codimer, tricyclopentadiene andmixtures thereof.
 3. An offset printing ink composition according toclaim 1, wherein said five-member cyclic compound and said Diels-Alderaddition product thereof (component A) is a concentrated distillateobtained by removing the major part of C₅ -fractions from a mixtureprepared by the thermal dimerization of cyclopentadiene andmethylcyclopentadiene contained in the C₅ -fractions of by-productcracked oils obtained by thermally cracking naphtha or the like at ahigh temperature.
 4. An offset printing ink composition according toclaim 1, wherein said five-member cyclic compound and said Diels-Alderaddition product thereof (component A) contains an unsaturated aromaticcompound in an amount not more than the amount of said five-membercyclic compound and said Diels-Alder addition product thereof.
 5. Anoffset printing ink composition according to claim 1, wherein saiddrying oil has an iodine value of not less than 120 and is selected fromthe group consisting of vegetable oils and fats, animal oils and fatsand mixtures thereof.
 6. An offset printing ink composition according toclaim 5, wherein said vegetable oil is selected from the groupconsisting of linseed oil, tung oil, soy-bean oil, dehydrated castoroil, boiled linseed oil, boiled tung oil, boiled soy-bean oil, boileddehydrated castor oil and mixtures thereof.
 7. An offset printing inkcomposition according to claim 1, wherein said fatty acid is selectedfrom the group consisting of myristic acid, palmitic acid, stearic acid,oleic acid, linoleic acid, linolenic acid, fatty acids of linseed oil,fatty acids of tall oil, tall oil mainly composed of fatty acids andmixtures thereof.
 8. An offset printing ink composition according toclaim 1, wherein said component C is selected from the group consistingof acrylic acid, methacrylic acid, maleic acid, maleic acid anhydride,tetrahydrophthalic acid and anhydride thereof, fumaric acid, citraconicacid, itaconic acid, fatty acids of drying oils and mixtures thereof. 9.An offset printing ink composition according to claim 1, wherein saidresin (II) modified with an acid is esterified with a monohydric orpolyhydric alcohol.
 10. An offset printing ink composition according toclaim 1, wherein said phenol is selected from the group consisting ofp-tert-butylphenol, sec-butylphenol, p-tert-octylphenol, nonylphenol andmixtures thereof.
 11. An offset printing ink composition according toclaim 1, further comprising 50 to 200 parts by weight of a hydrocarbonsolvent having a boiling point of from 200° to 350° C., and 10 to 100parts by weight of a drying oil, the content of an aromatic compound insaid hydrocarbon solvent being 50% by weight or less.
 12. An offsetprinting ink composition according to claim 11, wherein said hydrocarbonsolvent is a paraffin solvent.
 13. An offset printing ink compositionaccording to claim 1, further comprising 5 to 100 parts by weight of astraight-chain α-olefin based on 100 parts by weight of said component Ain addition to said component B.
 14. An offset printing ink compositionaccording to claim 13, wherein said straight-chain α-olefin has 4 to 40carbon atoms.
 15. An offset printing ink composition according to claim14, wherein said straight-chain α-olefin is selected from the groupconsisting of 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-dodecene,1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and mixturesthereof.